With the fast development of communication network, cell phones have been indispensible electronic products in daily life, they are required to have a smaller size but more functions; meanwhile, the requirement for a Subscriber Identity Module (SIM) card becomes higher. A cell phone is not only equipped with a SIM card and a Micro SD card, but also has a much higher requirement for the hot plug. Furthermore, the popularity of Micro SD card brings urgent need for the hot-plug function of the Micro SD card.
At present, various cell phones with the hot-plug function of SIM card are present in the market, which initially solve the problem that shutdown is necessary during the change of SIM card. However, for ordinary cell phones with hot-plug function, the plug-in and pull-out states of the SIM card are monitored by an electronic switch, and then corresponding handling is performed by a master chip. This design is not only complex but also occupies the space of a motherboard, which increases the product cost and, at the same time, goes against the development tendency that cell phones become smaller and smaller.